function res = fn_FF(x, T)

res = zeros(1, length(x));

res(-x/T>33) = x(-x/T>33);
res(-x/T<=33) = -T*log(1+exp(-(x(-x/T<=33))/T));


% if -x/T>33
%     res = x;
% else
%     res = -T*log(1 + exp(-x/T));
% end

end